1. Field of the Invention
The present invention generally relates to switches and switch testing apparatus. Specifically it relates to switches that are triggered by fluid flow and remote testing thereof.
2. Description of Related Art
To fight fires in modern buildings, firefighters use a wide variety of tools but are also regularly aided by systems within the building. Modern buildings almost universally include water-based fire protection systems to control or extinguish fires. Fire sprinkler systems generally follow a fairly standardized principle. A liquid firefighting material (generally water) is maintained in a series of pipes, generally under pressure, which are arranged throughout all areas of the building.
In a wet pipe system, water is actually stored within the pipes, whereas in a dry pipe system, water is stored external to the building while the pipes contained pressurized air, nitrogen, or other gas. Attached to these pipes are various sprinklers which, when activated, will spray the liquid into a predetermined area. When a fire situation is detected, sprinklers on the pipe structure are activated by heat. This opens them and allows them to spray water from the pipe system.
The heat activation is generally performed by a heat sensitive element, an integral part of the sprinkler, which is activated by the heat from the fire. Specifically, the sprinkler utilizes a “plug” holding it closed. The plug is damaged by heat which results in the pressurized water inside the pipes being pulled to and through the opening in the now activated sprinkler head. Generally, each sprinkler has its own heat sensitive element and is activated independent of all other sprinklers. This action dispenses the liquid on the fire and serves to control or extinguish the fire.
This system can be very effective because there is no reliance on notification systems or other separate components where a communication breakdown could occur. There is always concern in a fire protection system, that the fire could damage any form of notification system prior to it being able to provide notice. In the plug arrangement discussed above, there is very little possibility of the sprinkler system failing to activate due to damage from the fire. As the damage causes the activation, the system simply enters into a spray mode at that sprinkler. Further, the sprinkler will generally spray until the system is shut off as the water source is often municipal water lines providing a steady feed and there is no switch which can serve to replug the sprinkler once activated. Instead, the unit must be replaced.
Because of the fact that most fire protection systems utilize these type of heat activated sprinklers, they generally do not use smoke detectors or other forms of fire detection apparatus to activate the system. While this works from a fire fighting perspective, in a large building it is often necessary to notify both occupants of the building that the system has activated, and to notify the fire department that the system has activated so that they can come and fight the fire. Therefore, systems beyond those simply to activate the fire sprinkler are desirable as part of the system.
While some sprinkler systems utilize smoke detectors and other detection mechanisms to provide notification, others do not. Further, even if they include detection apparatus, it can be desirable to know if only smoke has been detected and/or if a sprinkler head has activated. Further, detection and notification systems can be damaged by the very fire that the sprinkler has reacted to prior to providing notification. Therefore, most sprinkler systems utilize a system to detect that a sprinkler head has activated as an alternative notification system.
While these detection systems can be simple or complex, most rely upon fluid flow within the pipes of the sprinkler system to detect that a sprinkler head has activated. In particular, when a sprinkler head (or multiple heads) activate, fluid in the pipes will go from a static condition, to a condition where the fluid is moving toward the activated head. This fluidic movement can be detected through the use of a flow detector which is placed in the fluid stream and when the flow detector detects fluid motion (“flow”), an alarm condition is activated to provide notification that water is being dispensed by the system.
Because fluid flow specifically indicates a sprinkler head activation, or a system failure resulting in water dispensing which is another potential emergency, the flow detector is an excellent form of notification of potential danger. Based on the output of a flow detector along with output of other detectors, information can also be gathered as to the potential location of a fire, or if there may be a damaged pipe which is generating flow in a non-fire situation. In a large office building, the ability to send emergency personnel to the correct location quickly can often decrease property damage and potentially save lives.
Flow detectors are more commonly used in wet-pipe systems and most are of relatively straight forward design. They generally comprise an elongated vane including a paddle which extends generally perpendicularly into a pipe in the system, often a large main pipe or riser so that movement of the fluid is detected wherever in the system it occurs. However, flow detectors may be placed on particular pipe components to assist in localizing the position of the flow. The water flow through the pipe forces the paddle forward, which then causes a trip switch at the other end to trip an internal switch activating the alarm condition.
The most common liquid used in fire protection systems is water because it is readily available, non-toxic, and quite effective in firefighting. Water, however, is an electrolyte which can enable electrochemical corrosion to occur where metal and oxygen are also present. Further, the water used in sprinkler systems is generally not pure and can contain a multitude of dissolved solids, water treatment chemicals, and microorganisms. These impurities can contribute to corrosion, including microbiologically induced corrosion, damaging pipes or other components that make up the water-based fire protection system when the system is prepared and “armed” awaiting a possible fire situation. The presence of trapped air (particularly the oxygen in the air) and how active a system is (how often it is drained and filled) will also contribute significantly to corrosion and its damaging effects in water-based fire protection systems.
The degradation of components such as flow detectors is an unavoidable consequence of the inclusion of water in the system. The presence of water within the piping can result in the failure of mechanical components to perform as intended when needed due to components becoming corroded while they are held in their “ready” state. Flow detectors and other types of mechanisms in a fire protection system are particularly susceptible to failure because they often sit for long periods of time in a ready state (switched off) and need to quickly adjust to a new state (switched on) upon the fire system activating. Because of the risk of failure of components such as flow detectors, it is generally desired to periodically test them to insure that they function.
While flow switches can be tested by flowing water through an inspection port (which creates flow through the system simulating an activated sprinkler), this system can be cumbersome. Therefore, it is often desirable to test flow switches remotely without need of flowing water through the entire fire sprinkler system. One system to test flow switches is described in U.S. Pat. No. 6,462,655. This system, while effective, is very complex in that it requires a localized fluid “loop” which is generated to create a limited area of fluid flow about the flow switch within the otherwise static pipe system. While it is effective at performing a flow test, and effectively tests that the flow switch will operate under an actual flow condition, the system is complex to construct, includes additional components vulnerable to corrosion, and is relatively expensive.